Range-finder.



No. 822,201. 7 PATENTED MAY 29, 1906. B. A. FISKE.

RANGE FINDER.

APPLICATION FILED SEPT. 27, 1905.

3 SHEETS-SHEET l.

E S S E N H W mnnzwia. GRANAM c0. Puam umomwums. wnsumcrou, o. a

No. 822,201. PATENTED MAY 29, 1906.

B. A. FISKE.

RANGE FINDER.

APPLICATION FILED .27 9o SEPT 1 5 a SHEETS-SHEBT 2.

No. 822,201 PATENTBD MAY 29, 1906.

B. A. PISKE:

RANGE FINDER.

APPLICATION FILED SEPT. 27, 1905. 3 SHEETSFSHEET a.

l|l n m @E MIMM v1 3 EEF INVENTOR W fi/ BM ATTORNEY UNITED sTATEs PATENTOFFIQE.

RANGE-FINDER.

Specification of Letters Patent.

Patented May 29, 1906.

Application filed September 27. 1905. Serial No- 280,285.

T0 to whom it may concern:

Be it known that I, BRADLEY A. FISKE, of the United States Navy, haveinvented a new and useful Improvement in Range-Finders, of which thefollowing is a specification.

The principle of my invention consists in establishing a proportionalrelation between, first, the range to be determined; second, a knownbaseline on the supporting-bar of the instrument; third, the amount ofapparent displacement of the images of the distant object due to therays diverging therefrom to the ends of the said baseline when saidimages by reflection and projection are referred to the same focal planeof observation, and, fourth, the focal length of the projecting device.

I As is hereinafter explained, the known terms in the proportion are thebase-line length and the focal length of the projecting device, andthese become a constant in any given instrument. In practice, therefore,it remains only to measure the amount of displacement of the images ofthe distant object as the same appearin the field of the eyepiece.

. This is done by a simple mechanical adjustment of a reflector wherebysaid images are brought into alinement. The observer then reads themeasurement on a micrometric scale marked once for all in correspondingterms of range.

It will be apparent that my device is a one observer range-finder whichpermits of instant range determination without resort to calculation andthat its operation requires no previous special education ormanipulative skill beyond that ordinarily required for the handling ofany instrument of precision.

As the accuracy of the device depends considerably upon itsconstruction, my invention further consists in certain mechanicalfeatures and combinations more particularly recited in the claims,whereby, first, the base line bar is prevented from deflection ordistortion; second, the instrument is equilibrated on a longitudinalaxis of the base-line bar; third, the instrument is supported so as tobe moved by the application of a very small force; fourth,the'instrument may be oscillated on its longitudinal axis of support;fifth, the instrument may be moved on a supporting-pivot over smallazimuth angles.

In the accompanying drawings similar numbers and letters of referenceindicate like parts.

' Figure 1 is a side elevation of the instrument mounted on its base,which maybe the top of a turret. Fig. 2 is a horizontal section on theline LE 00 of Fig. 3 of the box in which the telescopes and eyepiece aremounted and which contains the adjustable reflector. Fig. 3 is avertical section on the line y y of Fig. 2. Fig. 4 is a perspective viewshowing in detail one of the supports for the baseline bar. Fig. 5 is asection of one of the knife-edge supporting-blocks and beveled plateresting thereon. Fig. 6 is a plan view illustrating the effect ofdisplacement of the adjustable reflector. Fig. 7 is a plan view of theentire instrument. Fig. 8 is a plan view and partial section showing thedevice for moving the baseline bar over small azimuth angles. Fig. 9 isa plan view of one of the roller-supports of the base-line bar. Figs. 10and 11 show the images seen in the field of the instrument underconditions hereinafter explained. Fig. 12 is a diagram illustratingtrigonometrical relations.

I will first describe the mechanism.

1 is a bar of metal which carries the optical parts of the instrument.As hereinafter explained, an interval between two points on thelongitudinal axis of this bar consti tutes the baseline in thetrigonometrical determination of the range. Near one end of said bar issecured a cubical box 2, and fixed in one wall thereof is a telescope 3.In the opposite wall is secured the eyepiece 4. Near the other end ofbar 1 is a reflector 5, which is permanently fixed at an angle toreflect a ray C coming from a distant object T in a right linecoincident with the central axes of the telescope 3 and eyepiece 4.

Secured in another wall of box 2 with its central axis at right anglesto and intersecting the line joining the axes of telescope 3 andeyepiece 1 is a telescope 6. 7 is a vertical reflector, thereflecting-surface of which is rigorously parallel to thereflecting-surface of reflector 5. In vertical height the reflector 5extends only to the horizontal plane, which includes the axes of thetelescopes 3 and 6. The middle point of its upper edge is nor mallycoincident with the point of intersection of said axes. By reason ofthis construction all the rays, as C, which reach the eyepiece afterreflection from the reflector 5 are above the horizontal diameter on nof the field, Figs. 10 and 11, and all the rays, as D, which arereflected from the reflector 7 are below said diameter. The reflector 7is adjustable in the direction of the axis of tele- 4o turret-top, andhence is immovable.

50 posts.

scope 6. To this end it is mounted on a block 8, Figs. '2 and 3, whichslides in dovetail guides 9, secured to the bottom of box 2.

On each side of block 8 are projections extending over the guides 9, towhich projections are attached the ends of helical springs 10, theopposite ends of said springs being attached to lugs 11 inside the box.The springs hold the block 8 against the end of To the adjusting-screw12, which is received in a threadedboss on the wall of the box oppositeto that in which telescope 6 is secured. Then the screw 12 is turnedinward, the block 8, and hence the reflector 7, is moved toward I 5telescope 6, and when the screw 12 is turned in the opposite directionthe block 8, being retracted by springs 10, is moved away from telescope6.

The bar 1 is designed to be mounted on the top of a platform rotary inahorizontal plane,

such as the top of a warships turret, and to be carried over largeazimuth angles by the revolution of said platform. The top plate of sucha turret is represented at 13. It is 2 5 necessary, however, to supportsaid bar so as to realize three objects-viz., first, the maintenance ofthe bar in a true horizontal plane, or, in other words, the preventionof deflection or distortion; second, movement of the bar in azimuth overshort arcs around-a center about midway its length; third, oscillationof the bar over small angles around a longitudinal axis.

In order to maintain the bar in true hori- 5 zontal plane, I suspend itat three points in I 5 shown at 18, Fig. 5. This rounded extremity isreceived in a similarly-formed socket in the bottom of a cylindricalblock 19, the upper part of which is beveled to a knifeedge, Figs.

4 and 5. The blocks 19 turn freely on their On the upper side of the bar1 are bolted brackets 20 21 22, which extend over the slots throughwhich pass the posts 14 15 16. On the under side of these brackets aresecured inwardly-beveled plates 23, the angle of the bevel in which isgreater than the angle of bevel foriiiingthe knife-edge. The bar 1 issuspended, as stated, at three points by causing the beveled plates ofbrackets 20 l 21 22 to rest upon the knife-edges, and said knife-edgesare placed along the longitudinal axis of the bar, upon which axis thebar and parts supported thereby normally balance. Said axis is thereforenot in the central line of the bar, but at one side thereof in order tocompensate for the weight of the projectingseeeoii telescope 6. Theposts 14 and 16 are approximately equidistant from the middle post 15.The bar being thus suspended is prevented from deflecting. Because theangle of bevel of plates 23 is greater than the angle of bevel of thereceived knife-edges of blocks 19 the bar may be oscillated on saidknife-edges. The object of permitting such oscillation of the bar is toenable the observer to hold the telescopes in horizontal position and tokeep them correctly bearing upon the object despite departure of thebase on which the bar is supported from a horizontal plane. Where thebase is a turret-top, such departure occurs when the vessel is at seaand rolls or pitches.

The posts 14 and 16 each extend upwardly from downwardly-flanged plates24 25. Secured beneath said plates and upon the turret-top areupwardly-flanged plates 26 27. Between each pair of plates 24 26 and 2527 are rollers 28, journaled in side bars 29, Fig. 8. Said rollerspermit the bar 1 to be freely turned around the middle post 15 as acenter. They are shorter in length than the distance between the flangeson plates 26 27, as shown in Fig. 3.

The object of moving the bar 1 around post 15 as a center is to enableit to be laid parallel with the usual telescopic sights employed withturret-guns, since such sights are sometimes laid with their axesvarying slightly in azimuth from the direction of the axes of the gunsin order to make certain well-known allowances in sighting not necessaryhere to explain. The extent of movement of the telescope-sight, andhence the needful extent of movement of the bar 1 around post 15, issmall, and the latter is effected and controlled in my presentinstrument by the following means: Extending rearwardly from thedownwardlyflanged plate 25 are twoarms 30. A quick threaded screw 31 isj ournaled in one of said arms, and its extremity is seated in the otherarm. Between said arms and fixed on the turret-top is a nut 32, throughwhich screw 31 passes. By turning said screw in either direction the bar1 is swung on its pivot 15. The divergence of the path of bodilymovement of screw 32 from a straight line during said swinging ispermitted by making the threads of screw 31 fit loosely in nut 32.

I will now explain the optical principles in- .volved and the mode ofoperation of the instrument.

The focal lengths of the object-lens L of telescope 3 and of object-lens L of telescope 6 are the same. The focal plane common to bothtelescopes and also to the eyepiece 4 is represented by the line O P,Fig. 6. The base-line is the distance between the middle points of thesurfaces of reflectors 5 and 7. In practice this may measure fifteenfeet. distance L a may be 40.75 inches.

Assume an objectas, for example, as

The

fixed starso far distant from the instrument as that rays therefromproceeding to opposite ends of the base-line will be parallel. Rays, asC, reflected from reflector 5 and passing over reflector 7 will becomefocused at A, Fig. 6. Rays, as D, reflected from reflector 7 will alsobecome focused at the same point a. The partial images of the objectabove and below the horizontal field diameter m n will then coincide,and the object or star will appear as at E, Fig. 10. Assume now anobject the rays from which in proceeding to the extremities of thebase-line diverge and are not parallel'as, for example, one locatedwithin the terrestrial horizon while the rays, as C, from that objectproceed as before to the point a, Fig. 6. Other rays, as D, are focusedafter reflection from re Hector 7 to the point I) distant from a on thefocal plane 0 P. As the angle of divergence between said rays 0 Dincreases the distance between points I) and 6 correspondingly augments,or, in other words, the nearer the object approaches to the instrumentthe greater will be the distance a b.

It has already been stated that a fixed star (rays parallel) appears inthe field as at E, Fig. 10. Let the object be a vessels mast with flagthereon, which being near sends divergent rays to the ends of thebaseline. Then the focal points a, I) being separated, the parts of theobject will appear displaced on the horizontal field diameter m n by thedistance a b, or as shown at G, Fig. 10, where the upper part of themast is shown displaced to the right of the lower part by that distance.

Inasmuch as the distance a b on the focal plane O P varies inversely asthe distance or range of the object from the instrument, it follows thatthrough a determination of a b said range or distance of the object canbe found. This I accomplish in the following manner: Recurring to Fig.6, assume the reflector 7 to be moved by its screw 12 until the point I)coincides with the point a, or, in other words, until the reflectortakes the position indicated by the dotted lines. If the instrument wereoriginally sighted upon a fixed star (parallel rays) appearing, asstated, at E, Fig. 10, the result would now be to displace thehalf-image above the diameter m n to the left, or as shown at E, Fig.11. If, on the other hand, the instrument were originally sighted upon avessels mast (diverging rays) appearing, as stated, at G, Fig. 10, theresult would be to move the part of the image above the diameter m n tothe left, as seen through the inverting-eyepiece, and into coincidencewith the lower part, as shown at G, Fig. 11. Obviously the extent ofmovement of reflector 7 to accomplish the lastnamed result can easily bemeasured physically by any suitable micrometric device combined with thescrew 12, which will show the distance advanced by the screw perrotation and fraction of rotation thereof.

' Practically the object-lens L of the telescope 6 may be supposed tolie in the line joining the axes of telescope 3 and eyepiece 4, or, inother words, the length of telescope 6 may be neglected. The focallength of telescope 3 is known, being the distance from its object-lensL to the focal plane which includes the point a. Then if T, Fig. 12, bethe position of the object and A the middle point of reflector 5 Ac atAT La A T is the range or distance to be ascertained, and thereforeequals Aa La a?) As the numerator of the fraction is a constantdeterminable once for all for a given instrument, it becomes obviousthat the screw 12 may be provided with a micrometer cylinder-head 33,marked for ranges corresponding to different displacements of thereflector 7, and that the required range can be read therefrom in theusual way by means of the fixed index 34, Fig. 2.

In establishing the range-scale the infinitymark is determined byobserving a fixed star, for example, any instrumental errors ofconstruction being then corrected by bringing the upper and lowerhalf-images of the object into coincidence, as at E, Fig. 10.

In using the instrument the index 34 is set at the infinity-mark on thescale of cylinder 33, when the parts of the image of the distant objectwill appear separated, as illus trated at G, Fig. 10. The screw 12 isthen turned to move reflector 7 to the right of the observer, whichthrough the reversal of the images by the lenses will cause the upperdisplaced part of the image to move to the left of Fig. 10 until bothparts coincide, as at G, Fig. 11. The scale-reading of the range inyards or meters (shown by the index 34) is then taken.

I claim 1. Two telescopes disposed at right angles and reflectorsassociated therewith constructed to project two diverging groups of raysfrom a distant object to the same focal plane, and means for displacingin said plane the image due to one te escope with respect to the imagedue to the other telescope.

2. Two telescopes disposed at right angles and reflectors associatedtherewith constructed to project two diverging groups of rays from(adistant object to the same focal plane, and means for moving one of saidreflectors and thereby displacing in said plane the image due to onetelescope with respect to the image due to the other telescope.

ITO

I formed by one of saidtelescopes with respect to the image formed bythe other telescope.

5. Two telescopes disposed at an angle in the same plane, and havinglenses of the same focal length, reflectors associated with saidtelescopes and constructed to reflect the two partial images of adistant object projected by'said telescopes to the same focal plane, andmeans for displacing in said plane one of said partial images andbringing said image into alinement with the other partial image andthereby forming a complete image.

6. A support, and, located thereon, a telescope, an inclined reflectorfixed at a distance from said telescope and in the line of sightthereof, an eyepiece in line with said telescope, an inclined reflector1 between said telescope and eyepiece 2 parallel to said first-namedreflector 3 disposed with reference to the central axis of saidtelescope 4, and a second-telescope 1 at right angles to and 2 havingits central axis in the same plane as that of-said first telescope; thesaid eyepiece and telescopes having a common focal plane. Y

7. In a range-finder, a supporting-bar whereon is established anarbitrary base line, parallel reflectors on said bar at opposite ends ofsaid baseline, an eyepiece, means for projecting the image of a distantobject received by one reflector to the focal plane of said eyepiece,means for projecting another image ofsaid object to the second reflectorwhereby said image is reflected to the same focal plane, and means fordisplacing one image until it is alined with the other image.

8. In a range-finder, a supporting-bar, a

reflector at one end thereof, a chamber at the other end thereof, atelescope secured in one wall of said chamber and disposed parallel tosaid bar, an eyepiece secured in the opposite wall of said chamber, atelescope secured in another wall of said chamber and at right angles tosaid first telescope, a reflector in said chamber located at one side ofthe plane including the axes of said telescopes and eyepiece, and meansfor moving said last-named reflector in a path at right angles to theaxis of said first-named telescope.

9. In a range-finder, a base, optical members, a bar carrying saidmembers, a central pivot-support for said bar fixed on said base, andend supports for said bar movable on said base; the said supports havingrectilinear upper edges disposed in a line parallel to the longitudinalaxis of said bar, and the said bar having bearings receiving said edges.

' 10. In a range-finder comprising-an elongated bar and two telescopescarried by said bar, one of saidtelescopes being parallel to and theother at right angles to said bar, means for supporting andequilibrating said bar on an axis parallel to the axis of said firstnamed telescope.

11. In a range-finder, a base, optical members, a bar carrying saidmembers andmeans for supporting said bar on said base; the saidsupporting means being constructed and ar ranged to permit said bar tobe oscillated on a longitudinal axis independently of said base.

12. In a range-finder, a base, optical mem bers, a bar carrying saidmembers and having openings, supports extending upward from said baseand passing through said openings and means on said bar for suspendingthe same on the upper extremities of said supports. i g

13. In a range-finder, a base, optical members, a bar carrying saidmembersand having openings, su ports extending upward from said base anpassing throughsaid openings, means on said bar for suspending the sameon the upper extremities of said supports and means for moving said bar111 azimuth around. one toff said supports as a pivot.

14. In combination with and carrying the optical members of arange-finder, a bar and a support having a rectilinear upper edge, onwhich edge said bar isequilibrated.

15. In a range-finder, optical members, a bar, and a plurality ofsupports each having a rectilinear upper edge and the said edges beingin line,- the said bar carrying said optical members and itself carriedby and equilibrated on said support edges.

. 16. In a range-finder, optical members, a bar, a plurality of supportseach having a rectilinear upper edge and the said edges beingin line;the said bar carryin said optical members and itself carried by anequilibrated on said support edges, and means for moving said bar inazimuth around one of saidsupports as a pivot.

17. In a range-finder, a bar having a longitudinal groove, opticalmembers carried on said bar, a loose sleeve having at its upper .edge aknife-edge constructed to fit in said groove and a rod carrying saidsleeve.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

BRADLEY A. FISKE.

WVitnesses: 7 WM. H. SIEGMAN, PARK BENJAMIN, Jr.

ITO.

